Air heater



Dec. 8, 1925.

` B. S. HARRISON AIR HEATER 1%2 ,3 E.2 Sheets-Sheet 1 ed g. 24

'7 To TA cK Dec. '8, 1925 .y 1,564,567 B. S. HARRISON A'IR HEATER Filed Aug. 24, 1922 2 Sheets-Sheet 2 -ro STA CK Patentes Dec. s, 1925.

UNITED STATES Boar s. HARRISON, or CHICAGO,` ILLINOIS, ASsIeNOa 'ro nnYING SYSTEMS,

or CHICAGO, ILLINOIS, A

, 1,564,561 Parslvrv OFFICE.

y INC.,` cpRrOaATION or ILLINOIS.-

AIR HEATER.

Application led August 24, 1922. Serial No. 584,018.

To all whom t may concern.'

Be it known' that l, BURT S. HARRISON, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented a new and useful Improvement in Air Heaters, of

which the following is a specification.

This invention relates mainly to air heaters, such for instance as may be used in conl0 nection with lumber kilns, paint Shops, and other drying systems. L x The main objects of the invention are to rovide an improved form of air' heating urna-ce or combination of burner, combusytion chamber, and oven,'adapted to heat large quantities of air and capable of transferring substantially all of the heat from the flame and from the gases of combustion to the air to be heated before the gases of combustion leave the heater; vto provide a heater of the character described having a tortuous combustion chamber and passage-l way diminishing in area of cross section to accord substantially with the diminished volume of the air current as it cools in passing from the burner tuyre to the outlet, and so maintain a substantially constant flow speed; to provide an air heater of the character stated adapted to insure a steady forward movement of the gases, freefrom appreciable eddy currents; to rovide in such a heater a serially connecte group of liuc sections disposed horizontally one above another; to provide such a device adapted to operate on either gaseous, liquid or pulverized fuel; to provide the necessary heater parts of simple form, adapted for ready forming as by casting, and adapted to prevent unequal expansion and injurious strains under heat; to provide for ready access .to

the surfaces for inspection, cleaning and repairs; to provide joints such as may be depended upon to relieve the adjacent parts of expansion strains and yet be tight enough to prevent leakage or infiltration; to provide wall members or sections of improved con struction preferably in the form of castings,

to enclose the combustion zone and adapted to receive a refractory material cemented-y Ithereto, and without danger of breakage due to unequal expansion when under heat; to provide such aheater ill-standard unit secy tional form so that its capacity may be made greater or smaller by, the addition or sub` traction` of sections; andto provide for tiring the larger units from both ends, with centrally Pdisposed vertical passes.

An illustrative embodiment of this invention is shown in the accompanying drawings,-

in which'- through the heater at 1-1 on Fig. 2 and shows the arrangements of batiles in the combustion chamber. s

Fig. 2 is a vertical cross section .through the heater at 2-2 on Fig. l and shows the' combustion chamber and branched air flue -disposed symmetrically within the air chamtion a large capacity embodiment of the invention, in which two fuel tuyres are disposed in opposition to each other for ring at .both ends and in which the vertical passages are disposed alternately at the middle and ends of the horizontal ways.

In the construction shown the drawings, Figs. 1 to 5, the air heater as a whole comprises in combination, a burner in the form of a tuyre tube 1,l a combustion chamber 2, the initial or lower` section of which may be regarded as substantially a fire box, an air chamber 3 of iue like character surrounding said combustion chamber, and an outer insu ating chamber 4 for dead 4air surrounding -said air chamber together with certain structural members and details which will be described. The tortuous combustion chamber 2` extends upwardly'in successive' serially connected horizontal sections 5 sep L arated by the llames 6 and discharges its gases at the outlet 7 The air heating chamber or air flue 3 has an inlet 8 at the top on one side and dividing extends downwardly '105 on both sides of the combustion chamber 2. The .branches 9 unite at the bottom and discharge'throu h the outlet 10 on the opposite side in et .8.' Relative to the air passage 3 the outlet 10 is circuitously` remote from' the inlet 8, whereby a substantial heatiio . 60 Fig. 1 is a vertical longitudinal section ing time element is assured for the air to be treated.

structurally lthe eater as a whole oo mprises an outer wall r casingll of heat insulating character, Aan air flue casing 12 of sheet metal, and the furnace pro er made up mainly of cast wall plates and ttings to be described.

The said 'furnace or combustion part includes side wall Asections 13, end wall sections 14 and top and bottom wall sections 15 and 16 respectively, all detachably fastened together by means of bolts 17 to form a ame and gas chamber.

Said chamber is lined with refractory plates 18 cementedI to the inner sides of the said cast wall plates 13, 14 and 16 though at the .top these lining plates may be omitted by 'reason of the -lower temperatures of the fuel chamber 2. The plates 18`have beveled edges as shown in Fig. 2 whereby grooves are provided to receive the edges of the battles 6 for suplporting'the latter. The baffles also help to old the plate 18 in place. The vertically spaced refractory baliies 6 divide thel interior of the heater into the severa-l horizontal gas passages 5 one above another, so as toretai'd the passage of the gases'ofcombustion and provide a time element suliicient to permit the ases to dischargetheir heat through the wallg plates 18 and 14, etc., to the downwardly moving air in air chamber 3.

The`baies 6, for the sake of inthe size and shape of the wall plates, are equally spaced, but in order to provide for constant gas How speed in the tortuous chamber 2 for the contracting flue gases the walls 13 are made to converge u wardly, as shown in Fig. 2. whereby the re iue sections vrange from a thcktrapezoiclal shape near the bottom to a thin shape of this character near the top. This form of flue is practically free from eddy currents and is highly ei`ncient for the purpose here involved.

The walls of the combustion chamber are provided with flanges 19 adapted for fasten ing the cast metal plates together by means of the bolts 17. These anges are spaced apart somewhat when the wall plates are assembled and the joint space between is mainly occupied-by. a snug fitting strip 2O which may be of cast iron and which is perforated, as at 21, to receive said bolts. In o rder to make the joint gas'tight, a ocket is provided between the inner edge o `strip 20 and the bottom of the space or roove between ianges, which pocket is occupied by 0 a high temperature, flexible packin 22, which may well consist of pure asestos roving. 4

In order to rovide for ready access to the interior o the combustion chamber, hand holes are provided which are normally gas near the discharge end of the iue orf uniformity gradually cooling and occupied by plugs 23. The inner end ofeach lug is bevelled to t the correspondinly evelled hole 24 of the furnace plates. e outer wall or casing plate is provided with a much larger hole 25 which is normally closed by a coverplate 26 secured detachablyqf by screws 27. The plate 12 is provided wit a hole 28 in axial alinement with the holes 24 and 25 and receives the plug 23 snugly therein. Said plate 12 is provided with ex- `terior washers 29 fitting around the holes 28 and said washers being secured to bushings 30 by means of screws 3l. The bushings 30 serve as spacers between the plates 12 and 14, see Fig. 4, and are secured to the latter by bolts 32.

The furnace plates are provided with-extended radiating'surface means in the form of tins 33 integrally therewith, which fins are disposed vertically as well, shown by Figs. 2 and 5.

Referring to Fig. 6,. it will be seen that this invention may be embodied in a double burner furnace 34 provided with a plurality of horizontal ilues 35, disposed one above another, and the lowermost being provided with two inlet tuyresfone at each end. The lowermost flue is provided with an outlet 36 in the middle of its upper wall. The secondA fiue is provided with two outlets, olie at each end 37. f This arrangement alternates up to the top flue, which opens centrally into the discharge flue 38 leading to the stack, not shown.

It is tobe understood that the 'general construction of the double burner heater is substantially like that of the single burner heater, eXce t as above explained. It is provided with and holes at one end to permit of access to the interior for cleaning, as in the single burnerheater, and the various lparts and sections are formed in substantialy the same manner and are fastened together by bolts and screws in a demountablc manner, as will be understood. In this instance the wall plates are made in /five sections V39, though it is to be understood that this may be varied to suit the capacity required. For the sake of symmetry the number of sections may to advantage be an odd number, as for instance, 3, 5, 7, or 9, etc.

Although but two specific embodiments of this invention are herein shown, it is to bey Aunderstood that no attempt has been made to show all practical embodiments, and it is to be understood that some of the details' may be altered or omitted, without departing from the s irit of this invention, as defined by the fo owing claims:

I claim:

1. An air heater comprising, in combination a closed air chamber having an inlet and an outlet at points in effectfremote from each other along the line of travel ofthe air and a furnace proper contained therein including a fire box part and a combustion chamber merging therewith, said furnace being formed with upwardly convergent- Walls and being provided with horizontally disposed baiiles spaced apart vertically, the convergence of the walls being adapted to accommodate a substantially constant velocity of the gradually cooling products of combustion, said furnace having an inlet for the fuel in its lower part und an outlet for the gases of combustion in its upper part.

2. An air heater comprising, in combination, an air chamber having an inlet and an outlet at points circuitously remote from each other, whereby a substantial heating time interval is provided for the passage of each and every atom or unit of air through the heater and a furnace proper contained therein including a fire box part and a cornbustion chamber merging therewith, said re box and combustion chamber being conduit like in character and formed with horizontal baffles and upwardly*convergentv walls to maintain a substantially constant i'elocitj,v of the gradually cooling and shrinking products of combustion, said furnace havin an inlet for the fuel in its lower part and an outlet for the gases of combustion in its upper part.

Signed at Chicago this 22nd day of August 1922.

BURT S. HARRISON., 

